The present invention relates to the fuel tank filler neck connected to the gas tank of an automobile.
Gas tank fuel systems with reduced gasoline vapor loss are becoming increasingly important in the automobile industry to reduce needless loss of fuel. The typical solution to this problem has been to reduce the diameter of at least a section of the fuel tank filler neck. Though this approach has been somewhat successful, it is limited because as the diameter of the filler neck is decreased, the resistance to flow of the gasoline is increased. The increased resistance causes the fill neck to become filled during vehicle refueling thereby blocking release of any pressure buildup and causing the fuel nozzle to shut off prematurely before the fuel tank is full. Another consideration in preventing the loss of fuel, is the permeability of the materials from which the fuel tank system is made. Fuel vapors escape by diffusing through the various types of mild steels of which components of fuel tank systems are typically made. This fuel escape is particularly apparent after the mild steel components have corroded to any degree.
Another disadvantage of the current methods of reducing gasoline vapor losses is that typically the end of the gas line filler neck is flared out in order to provide a sufficient diameter to accept the gas nozzle during refueling. These filler necks are often made by a process of repeated reductions and expansions of a seamed welded tube. Accordingly, there is an increasing tendency for the integrity of the weld to leak as thinner diameter tubes are utilized.
The filler neck for receiving a fuel supply nozzle for a motor vehicle fuel tank includes a one-piece seamless funnel member having a tubular body. The funnel member defines in off-set axial relation a relatively large inlet opening adapted for attachment to a receptor for the nozzle and a relatively small necked down outlet opening adapted for attachment to the inlet of an elongated tubular member in communication with the fuel tank. The offset relationship of the inlet and outlet opening induces a swirling motion in the fuel flow as the fuel proceeds towards the fuel tank. The resultant swirl motion of the flowing fuel leaves an opening through which any pressure buildup in the fuel tank may be vented. The spiraling motion of the fuel through the narrow elongated tube member also assists in preventing fuel vapors from escaping during refueling because of an induced suctioning effect that is created by the spiraling motion of the fuel through a narrow cavity.
In another embodiment of the invention, the seamless funnel member is drawn and provided with an attachment portion adjacent to the inlet opening for attaching a gas nozzle receptor to the funnel member. The seamless surface of the filler neck allows for the receptor to protrude into the filler neck and form a seal to the inner surface of the filler neck.
In still another embodiment of the invention, the seamless funnel member is attached to the elongated member inlet by either a braised joint, an adhesive joint, or a resistance welded joint.
In yet another embodiment of the invention, the seamless filler neck is provided with an anti-corrosive coating.
In the preferred embodiment of the invention, the relatively large diameter section forming the inlet opening into which the gas nozzle is positioned and a spaced-apart relatively smaller diameter tubular section forming the outlet opening are in an axially offset relationship. These tubular sections are connected to one another by a tapered section which gradually blends from the large diameter section to the small diameter section. In a refinement of this embodiment, the tapered section intersects the large diameter section at an elliptically-shaped junction which lies in a plane inclined 60-85xc2x0 from the axis of the tubular sections. In a further refinement of this embodiment, the funnel inlet opening has a diameter D1 and the tubular section has a diameter D2 with a coaxial offset at a distance X where 0.1D2 is less than X which is less than 0.3D2, and where D1 is at least one and a half times D2. In yet another refinement of this embodiment of the invention, the funnel inlet axial offset is sufficient to achieve fuel swirl during fuel filling.
In another embodiment of the invention, the funnel inlet opening has a diameter D-1 and the outlet opening has a diameter D-2 where D-1 is at least one and a half times D-2. In a refinement of this embodiment, D2 is less than 35 mm. In a further refinement of this embodiment, D2 is less than 30 mm.
This invention also includes a method of manufacturing the filler neck for a motor vehicle fuel tank. First, the filler neck is formed by deep-drawing a seamless funnel member having an elongated tubular body with an enlarged inlet at one end and a relatively small outlet at the opposite end. A length of butt-seam tubing is cut to form a tubular member of desired length. An end of the tubular member is telescopically aligned with the outlet of the funnel member to securely join the funnel and tubular members together. The tubular member is bent to a desired shape. A nozzle receptor is attached to the funnel member adjacent the funnel inlet. In a refinement of the method, the configuration is then leak tested to verify the integrity of joining the funnel member to the tubular member and the attachment of the nozzle receptor to the funnel member, and the integrity of the butt-seam joint and the tubular member subsequent to bending. The funnel member is attached to the tubular member by braising, adhesive bonding, or welding. In yet another refinement of the method, a portion of the filler neck is configured to induce a sufficient swirl to create a hollow passage for suctioning fuel vapors to prevent their escape during refueling and to provide a vent passage for any pressure buildup in the fuel tank.
Accordingly, it is an object of the present invention to provide an improved fuel tank filler neck.
Another object of the present invention is to provide an improved fuel tank filler neck that inhibits the escape of gasoline vapors from the fuel tank.
Still another object of the present invention is to provide an improved fuel tank filler neck that is inexpensive to fabricate.
Still another object of the present invention is to provide an improved fuel tank filler neck that vents pressure buildup created in the fuel tank during refueling.
Still another object of the present invention is to provide an improved fuel tank filler neck that does not leak.
Yet another object of the present invention is to provide an improved method for fabricating the fuel tank filler neck of the foregoing objects.
Another more specific object of the invention is a method for forming a filler neck for a motor vehicle fuel tank by deep-drawing a seamless funnel member having an elongated tubular body with an enlarged inlet at one end and a relatively small outlet at the opposite end. A length of butt-seam tubing is cut to form a tubular member of desired length. An end of the tubular member is telescopically aligned with the outlet of the funnel member and securely joining the funnel and tubular members together. The tubular member is bent to a desired shape. A nozzle receptor is attached to the funnel member adjacent the funnel inlet.
Another more specific object in the method of the last mentioned object includes a portion of the filler neck configured to induce a sufficient swirl to create a hollow passage for venting vapors from the gas tank during fuel filling.
In carrying out the above objects and other objects and features of the present invention, a fuel tank filler neck is described in a mounting relationship to the vehicle fuel tank. The fuel tank filler neck and the method for its manufacture provide advantages to an automobile manufacturer by reducing escape of gasoline vapors from the fuel tank, by permitting simple manufacturing of the filler neck, and by reducing attendant costs.
The above objects and other objects, features, and advantages of the present invention are readily apparent from the following detailed description of the best mode for carrying out the invention whin taken in connection with the accompanying drawings.